Someone who in real life might be either a loser, dork, dweeb or idiot but is a snob online because the web is famous for its anonymity.
George gets online after work from McD's and goes to YourFacebook.com, sees someone who commented one of his high brow posts to his wall.
He in turn retorts with something equally high brow but with an air of snobbery.
He then gets a slew of "What a websnob!" comments back.
George feels that his opinion is more important than ANY else's and because it does not matter if he is a jerk because no one really knows him in real life, he spews his high brow crap everywhere he can.
This is closely related to the webtard, the difference being usually in perceived intellect.